Libscore doesn't provide a "score" so to say, but rather shows marginal library usage based on a regular crawl of the top 1 million sites. Think of Libscore as a informational tool to allow a lib author to see WHO is using their open source javascript library. Shortly, users will be able to see how libraries are trending over time.
For those who are interested, I've written up a guide explaining Libscore's intentions and downsides. The tool will never be perfect, but we think it serves its purpose: http://medium.com/@Shapiro/intro...
FontReach
Mandate
VC Sheet